Sound box



@@Waaf/ sept.1s,1923, 154ml@ A.. ENGNELL -SOUND BOX voriginal Filed March 20', 1919' Patented Sept. 18, 1923.

IES

i AXEL ENGNELL, OF CHICAGO, ILLINOIS.

SOUND BOX.

Application-filed March 20, 1919, Serial No. 283,784. Renewed July 9, 1923.

T o all w hom t may concern Be it known that I, nxrL ENGNELL, a citizen of the 'United States', residing at Chicago, in the county of Cook and State of Illinois. have invented certain new and useful Improvements in Sound Boxes, of which the following is a specification.

Myinvention relates to sound boxes and particularlyto novel means of *mounting the stylus bar on the sound box.

Among the objections to theV present. style of mounting a stylus on a sound box is that when the stylus bar is moved by the undulations in the record groove, the movement o f the diaphragm is affected to a certain extent when the movement of the needle is considerable. In sound boxes employing springs for mounting the stylus arm, the springs tend to dampen the vibrations of the diaphragm and conversely it is necessary that the diaphragm exert some influence to overcome spring resistance when the vibrations of the needle are out of the ordinary.

One of the objects of my invention is to provide a stylus bar mounting` for sound boxes which will eliminate the.` undesirable relationship between the diaphragm and the stylus arm mounting to remove any dampening effect on the diaphragm.

Another object is to provide a stylus arm mounting for sound boxes which will permit proper reproduction of sounds without dampening or otherwise retarding the effectiveness of the diaphragm.

A further object is to improve stylus arm mountings for sound boxes for successfulV commercial use.

Generally speaking I accomplish the objects of my invention by providing a knife edge engagement between the stylus arm and the sound box and mounting the tension spring wholly 'on the stylus arm so that the same may. be movable with the arm as the diaphragm is vibrated.

These and other objects of my invention will be apparent from an inspection of the drawings wherein- Figure 1 is a front elevational view of a sound box provided with the preferred embodiment of my invention.

Figure 2 is a back elevational view of the sound box in Figure 1, Va portion of the parts being shown in section.

Figure 3 is a vertical sectional view of my invention, and

Figure 4 is an enlarged sectional view taken in the plane of line 4-4 of Figure 1 showing the preferred means of mounting the stylus arm on the sound box.

In the form which I have chosen to illustrate my invention, I provide a sound box having a substantially solid back member 5 which has a centrally disposed opening 6 therethrough vfor transmittal of the sound to the tone arm. The diaphragm 7 is mounted between the usual resilient washers 8 and held in place by a ring 9 secured to the back plate 5 by screws 10 or other sniff able fastening means. Preferably, the screws are inserted through the back of the sound box. The lower portion of the back member 5 is provided with an extension 11 the purpose of which will be explained later.

Referring more particularly to Figure 3, it will be observed that the stylus arm is an integral member fastened at its upper end by means of an inside screw 12 to the center of the diaphragm 7 and provided at its lower end with a needle receiving aperture 13 having the usual set screw 14 for positioning the needle 15 in operative position. For supporting the stylus arm on thtl sound box, I employ a pair of knife edged members M3 and 17 (Fig. 4) adapted to en gage recesses 18 in the front face of the downwardly extending projection 11 of the sound box back. Preferably the members 16 and 17 are spaced apart as shown in the drawings. In the back side of the projection 11 I form a pointed recess 19 into which `projects a pointed pin 20. The pin member 20 is riveted or otherwise secured to a fiat spring 21 mounted as seen in Fig. 3 at some distance from the back of the projection 11. Screws 22 and 23 retain the spring 21 under tension which screws are in threaded engagementwith the lower portion of the stylus arm, the screw 22 engaging the stylus arm below the bottom of the projection 11, and the screw 23 above the lower end thereof, projection 11 being formed with a suitably disposed aperture 24 through which the screw 23 extends, and*y in which the screw is permitted freedom of bodily movement. The engaging edges of the knife members 16 and 17 and the point of the pin 2O I arrange to engage the extension member 11 in the same horizontal plane and in the same vertical plane so that any rocking movement of the stylus arm on the projection. 11 will prevent any vfriction as' the arm is moved and by reason of the -linek and point contacts, resistance and' friction is reduced to a minimum. Furthermore, such an arrangement permits rocking the vsylus arm on the support in such manner that no tension `is placed upon the spring when so rocked. Consequently,

the springdoes not tend to opposemove- 'ment' of the diaphragm Vas the same is 'v1-1 'brated when the needle is in engagement Y' with the sound groovesof the record. The

"grippingengagenient between the vknife degree of `freedom of movement of the stylus arm and'consequently the vibration ol the diaphragm may .be regulated within certain limits by tensioning or loosening the spring 2l which will vary the degree of edges V16' and 17 and the point 20 with; the socket-sor recesses with which these are 1n. engagement. Such an arrangement permits s free oscillation of the stylus arm with minimumresistance thereto resulting4 'in per- -feetY reproduction of sounds that are but lightly recorded on the record and further-V more, reducing 'the wear of the'recordby reason of the fact that neithervthe spring nor the diaphragm tend to oppose movei' ment of the needle as the same is in the record groove. Furthermore, such mounting serves to keep'the diaphragm ina neutral plane and to prevent creation of overtones as a result. spring on a seat suoli as disclosed in my invention, permits the stylus arm jto oseillate Freely about the fulcrum point as the fulcrum point or' the spring is in line with the 'fulcrum `point of the-stylus bar, hence no A sound box construction includingV 11"" support. a stylus bar, means lfor' mountingr said stylus baron said support,said meansV including bearinp` means carried byr'said bar and engaging' said support,^bcaring means engaging the oppositefside of aid support, said "plurality of bearing meansV dei'ininp; the axis of oscillation ot said The mounting` of the-V stylus bar, and' a plurality of members` mounted on said bar` on opposite sidesof said axis 'of oscillation tor maintainingsaid bearf ingr means in engagement With said support.

' Signed at Chicago, Illinois, this 18th day of March, 1.919.

AXEL nNoNuiin 

